Planar inverted F antennas (PIFA) are widely used as internal antenna for hand-portable radio communication terminals, such as mobile cellular telephones. However, a PIFA requires the antenna element to be mounted over 6 mm from the ground plane, as the PIFA bandwidth is proportional to this separation distance.
If the height of the antenna element above the ground plane is decreased, the bandwidth decreases and the antenna is unable to adequately cover EGSM (or UGSM) band. Typically a PIFA needs over 6 mm height to have enough bandwidth and efficiency for EGSM. If the height is decreased below 6 mm the PIFA cannot cover the EGSM band adequately.
If the PIFA height is increased, the bandwidth increases and the antenna is able to adequately cover both USGSM and EGSM bands, but the volume occupied by the antenna increases.
This is undesirable in hand-portable cellular radio terminals, such as mobile cellular telephones.
It would therefore be desirable to provide a low profile, multiband antenna.